Matching Questions
Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used. a) 960 nm b) magnesium c) ATP synthase d) chloroplasts e) thylakoids f) copper g) β-carotene h) 680 nm i) FAD j) chlorophyll a k) ferredoxin b
468
____________ This is where photosynthesis takes place.469
____________ These membranous structures in a chloroplast are stacked, flattened disks.470
____________ This is the principal photoreceptor in chloroplasts of green plants.471
____________ Chlorophyll a contains this ion in the center of the tetrapyrole.472
____________ Plastocyanin requires this cofactor for activity.473
____________ This is the prosthetic group of ferredoxin-NADP+ reductase.474
____________ This is another name for the CF1-CF0 complex.475
____________ This is one of the accessory pigments in plants.476
____________ This electron carrier of photosystem I is an iron-sulfur protein.Fill-in-the-Blank Questions
478
The inner membrane of a chloroplast surrounds a space called the .479
The process in which a positive charge forms on one molecule by the loss of a photoexcited electron, and a negative charge forms on another by the gain of an electron is referred to as .480
is the receptor of excited electrons from P680.481
P700 is the pigment reaction center for .482
The manganese center of photosystem II converts to .483
Electrons flow from photosystem I to photosystem II through the complex.484
In the light reactions of photosynthesis, the cooperation between photosystem I and photosystem II creates a flow of electrons from H2O to .485
The light-induced electron transfer in photosynthesis results in the transfer of into the thylakoid lumen.486
In ATP is generated without the concomitant formation of NADPH.487
The transfer of excitation energy from one molecule to one nearby through electromagnetic interactions is called .Multiple-Choice Questions
488
How is light used in photosynthesis?A) Light is necessary to make the chlorophyll green, so the pigment can transmit electrons. B) Light is used to generate high-energy electrons with great reducing potential.
C) Light provides heat energy for the chloroplasts.
D) Light is absorbed by oxygen, which is converted into water. E) None of the above.
489
Stacked and unstacked regions of the thylakoid are arranged such that A) photosystem I is located in the unstacked regions.B) photosystem II is located in the stacked region. C) ATP synthase occurs mainly in unstacked regions. D) A and C.
E) A, B, and C.
490
How many chloroplasts does a typical plant cell have?A) 1100 B) 200500 C) >1000 D) 500800 E) None of the above.
491
Light absorbed by a chlorophyll a causesA) an electron to move from the photon to the chlorophyll. B) an electron to move from ground state to an excited state. C) an electron to move to a neighboring water molecule. D) an electron to move from chlorophyll to ADP. E) None of the above.
492
In the overall stoichiometry of light reactions, eight photos of light generateA) 4 NADPH. D) B and C.
B) 4 NADH. E) A, B, and C.
C) 3 ATP.
493
The D1 and D2 subunits of photosystem II A) span the thylakoid membrane.B) are similar to each other.
C) are homologous to the L and M chains of the bacterial center. D) A and C.
E) A, B, and C.
494
Light absorption induces electron transfer from P680 toA) pheophytin. D) chlorophyll PP.
B) QH2. E) None of the above.
C) cytochrome c.
495
What is the original source of electrons used to neutralize the special pair in photosystem II? A) reduced cytochrome bfB) NADH
C) H2O
D) membrane lipids E) ferredoxin
496
Complete the following reaction for photosystem I: Pc(Cu+) + Fdox + light
A) Pc(Cu+) + Fd
ox light Pc (Cu+) + (Cu+) Fdred
B) Pc(Cu+) + Fd
ox light Pc (Cu2+) + Fdred
C) Pc(Cu+) + Fd
ox light Pc + Fdred(Cu2+)
D) Pc(Cu+) + Fd
ox light Pc– (Cu3+) + Fdred
E) None of the above.
497
The pathway of electron flow from H2O to NADP+ in photosynthesis is referred to asA) cooperative special pairs. D) photophosphorylation.
B) photorespiration. E) None of the above.
C) the Z scheme of photosynthesis.
498
How many protons are transferred into the thylakoid lumen after absorption of four photons? A) 2 B) 12 C) 18 D) 4 E) 8499
Which of the following is/are light harvesting molecules? A) vitamin DB) carotenoids C) chlorophyll b D) plastocyanin E) B and C.
500
Use the information in table 20.1 to answer the following question. Let us consider the overall light reaction in photosynthesis. NADP+ + H2O → NADPH + ½O2 + H+
Determine E ˊ0 for this reaction
A) -0.50 V B) +0.50 V C) -1.14 V D) +1.14 V E) -0.26 V
501
Determine the ΔG⁰ for this reaction: NADPˊ + + H2O → NADPH + ½O2 + H+ A) 96.5 kJ/mol B) –96.5 kJ/mol C) 50.18 kJ/mol D) –220..02 kJ/mol E) 220.02 kJ/mol
502
What evidence exists to support an endosymbiotic event for the formation of a chloroplast? The DNA of the chloroplast and the cyanobacteriumA) is arranged in operons. B) is linear.
C) has multiple start sites for DNA replication. D) encodes all chloroplast proteins.
E) contains both chlorophyll and mitochondrial genes.
503
What is the implication of the difference in permeability of the mitochondrial membrane vs. the thylakoid membrane to Mg2+ and Cl-?A) The thylakoid membrane is less permeable to Mg+, Cl-, and H+ and therefore more energy is
needed to pump protons across the membrane.
B) The mitochondrial membrane, being permeable to Mg2+ and Cl- means that electron flow only
occurs with transport of 1 Mg2+ and one Cl-.
C) The thylakoid membrane, being permeable to Mg2+ and Cl- means that electron flow only occurs
with transport of 1 Mg2+ and one Cl-.
D) The mitochondrial membrane, being permeable to Mg2+ and Cl- means that although protons are
pumped across the membrane, no membrane potential is generated.
E) The thylakoid membrane, being permeable to Mg2+ and Cl- means that although protons are
pumped across the membrane, no membrane potential is generated.
Short-Answer Questions
504
Write out the reaction for photosynthetic production of carbohydrates and oxygen.505
Humans do not produce energy by photosynthesis. Why, then, is this process critical to our survival?506
How is a chloroplast similar to a mitochondrion?507
Why are chlorophylls good candidates for photoreceptors?508
How is energy transferred from a photoreceptor molecule to photosystem II?510
What are the likely reasons that manganese evolved as the ion used in photosystem II?511
Describe the process of cyclic photophosphorylation.512
Give the overall net equation as catalyzed by the “Z scheme” of photosynthesis.513
Describe the path of electrons in photosystem I.P700 Plastocyanin Chlorophyll (Ao) Quinone (A1) 4Fe-4S Ferredoxin
514
Treatment of chloroplasts with KCN inhibits photophosphorylation, presumably at the level of plastocyanin. Predict the effect of KCN on a plant’s ability to perform cyclicphotophosphorylation.